Emissions Nebulae Ha; is there any point in taking Lum data?

[Notty]

I got some Ha LRGB data for the Heart nebula last week. I have 30 mins Lum, and 90 mins each of Ha R,G,B.  I have been playing around with processing.  My Ha data as you would expect shows beautiful contrast and detail from similar exposure times as the RGB.  I have attempted various combinations of Ha+RGB (Lum as Ha+synthetic from RGB), L+RGB (R=R+Ha) and LRGB (Lum=Lum+Ha) and finally pure Ha as luminance with no synthetic addition to Lum from RGB.  I'm processing in Startools.

In every single combination where the Ha is mixed with anything else as Lum, I lose almost all the Ha honey and get diminished detail and increased noise.  The only way to get a decent colourised image is to ignore the RGB data in the Ha Lum.  My question is, is this my data, my processing, or a combination of both?  Should I have taken much more Lum at the expense of RG&B do you think?  Any advice appreciated.  I'm reasonably happy with my result for a first go with this camera, but am scratching my head a little at whether my approach is flawed.  Thank you!

 

[Adreneline]

I don't know the right answers to your questions I can only comment based on my personal experience of using an ED80+ASI1600 and LRGB+Ha filters.

Living in a Bortle 5 area my personal experience of taking Luminance is that it contributes nothing of value in the final image; it is better to spend the time taking more R,G and B. Maybe my negative experience with L is due to my own processing shortcomings. All my Lum subs seem to do is to exacerbate the light pollution problem I have in this location.

I believe it is always preferable to combine Ha with the R. I combine Ha and R in Photoshop by copying the R layer and adding Ha as a 'lighten' layer.  I experiment with the opacity of the Ha layer to get the best result. I then replace the R layer with the new R+Ha layer.

I'm afraid I have no experience at all of StarTools so I don't know what is possible in terms of adding Ha to RGB.

Regarding your image above I have to say I cannot recall seeing that much green before in the Heart nebula - very unusual.

HTH

Adrian

 

[Wyvernp]

Hi, as a disclaimer I have no direct experience with this at all.  I have heard of people using light pollution or multi band filters to capture their luminance data because of light pollution. Once my Mono camera and filter wheel arrive I'm going to be using https://www.baader-planetarium.com/en/baader-uhc-s--l-booster-filter.html.

Not sure if that will help in any way.

[Notty]

1 hour ago, Adreneline said:

I don't know the right answers to your questions I can only comment based on my personal experience of using an ED80+ASI1600 and LRGB+Ha filters.

Living in a Bortle 5 area my personal experience of taking Luminance is that it contributes nothing of value in the final image; it is better to spend the time taking more R,G and B. Maybe my negative experience with L is due to my own processing shortcomings. All my Lum subs seem to do is to exacerbate the light pollution problem I have in this location.

I believe it is always preferable to combine Ha with the R. I combine Ha and R in Photoshop by copying the R layer and adding Ha as a 'lighten' layer.  I experiment with the opacity of the Ha layer to get the best result. I then replace the R layer with the new R+Ha layer.

I'm afraid I have no experience at all of StarTools so I don't know what is possible in terms of adding Ha to RGB.

Regarding your image above I have to say I cannot recall seeing that much green before in the Heart nebula - very unusual.

HTH

Adrian

 

Thanks, you've confirmed my suspicions.  My LP is pretty awful (no idea what a Bortle is) so I guess my RGB data is just bringing noise to the party.

Yes I noticed the Green too. I said I way happy with the image, I didn't say it was any good!  The ability to remove the green currently resides just the other side of my abilities 😉

Thanks for the reply. Andy

[Notty]

1 hour ago, Wyvernp said:

Hi, as a disclaimer I have no direct experience with this at all.  I have heard of people using light pollution or multi band filters to capture their luminance data because of light pollution. Once my Mono camera and filter wheel arrive I'm going to be using https://www.baader-planetarium.com/en/baader-uhc-s--l-booster-filter.html.

Not sure if that will help in any way.

Thanks for that. I've currently got a Baader Neodymium filter in the train, but maybe the one above is worth a look.

[Wyvernp]

1 minute ago, Notty said:

Thanks for that. I've currently got a Baader Neodymium filter in the train, but maybe the one above is worth a look.

No worries, it's not arrived yet so can't properly recommend it at all. Hopefully someone else on the forum has experience with it. My reason for buying is I live in a bortle 5 and the lum filter that came with my zwo set won't block any of the lp.

[Adreneline]

19 minutes ago, Notty said:

My LP is pretty awful (no idea what a Bortle is) so I guess my RGB data is just bringing noise to the party.

I think it may be the L that is bringing noise as well. I think it might be worth a try not using the L just to see what you get.

If you use Ha as L it tends to give the image a characteristic pink colouring.

I am sorry I cannot help with reducing green in StarTools; I used PixInsight to reduce the green but the colour balance still looks strange even though the individual histograms are essentially aligned. I also moved the black point a little to reveal a little more of the nebulosity.

It's a tricky business!

HTH

Adrian

[Notty]

47 minutes ago, Adreneline said:

I think it may be the L that is bringing noise as well. I think it might be worth a try not using the L just to see what you get.

If you use Ha as L it tends to give the image a characteristic pink colouring.

I am sorry I cannot help with reducing green in StarTools; I used PixInsight to reduce the green but the colour balance still looks strange even though the individual histograms are essentially aligned. I also moved the black point a little to reveal a little more of the nebulosity.

It's a tricky business!

HTH

Adrian

Yes, I gave up with L and am just using pure Ha as L. If I combine with a synthetic from RGB it looks terrible.  Anyway I think I've reduced the green, but at the price of a lot of nebulosity. H hum! That's my trade off using Startools, which I think is a blindingly good bit of software for the price which gives me 100x what I was getting in photoshop, but most people seem to use PI and given the time I have for this anyway it's a learning curve too far! Thanks for your help anyway, I'll have another go next year no doubt!

 

[Adreneline]

13 minutes ago, Notty said:

most people seem to use PI

It is true many people use PI but a very significant number also use PS - exclusively - with the help of books like this.

I think you've got some very good data and one thing you might like to consider is uploading your individual L, R, G, B and Ha masters so others can have a go and see what they can produce. You could always use something like DeepSpaceStacker to produce the calibrated masters.

When using PS have you used plug-in/actions like Annie's Astro Actions or Astronomy Tools - these represent excellent value for money and can be very helpful - I particularly like AAA at just $15.

Hopefully we won't have to wait until next year to see another image! I'm certainly hoping there will be some clear nights  

Good luck!

Adrian

[Notty]

8 minutes ago, Adreneline said:

It is true many people use PI but a very significant number also use PS - exclusively - with the help of books like this.

I think you've got some very good data and one thing you might like to consider is uploading your individual L, R, G, B and Ha masters so others can have a go and see what they can produce. You could always use something like DeepSpaceStacker to produce the calibrated masters.

When using PS have you used plug-in/actions like Annie's Astro Actions or Astronomy Tools - these represent excellent value for money and can be very helpful - I particularly like AAA at just $15.

Hopefully we won't have to wait until next year to see another image! I'm certainly hoping there will be some clear nights  

Good luck!

Adrian

Thanks Adrian, well I'd already created a shared dropbox folder with them in so it would be a shame not to share them! I haven't bothered with the L channel, I only had 30 mins anyway and forgot to copy it to my ssd before I left home for the week (key worker, I am lucky enough to be allowed!) yesterday. I have both full and 50% binned RGB but they didn't seem to make much difference. Here is the link on the offchance, though I expect everybody is busy processing last weeks 3 stunning nights harvest!  They're calibrated with darks flats and flat darks and aligned.

https://www.dropbox.com/sh/fpijc9ejhkxrz7r/AAAKfozTM55uWVF2bq7t5QGXa?dl=0

 

[Adreneline]

48 minutes ago, Notty said:

They're calibrated with darks flats and flat darks and aligned.

Well this is a quick go - registered and background extracted and RGB channel combined and stretched in PI.

The Ha was layered with R in PS and then all the rest of the colour enhancement and noise reduction in PS.

I might try the binned images tomorrow but this is more the sort of colour I would expect for the Heart using Ha-RGB.

Hopefully someone else will have a go who has more skill than me in RGB processing.

Adrian

 

[jager945]

Hi,

I had a quick look at the datasets. While the Ha signal is really nice, it seems the R, G and B data has all sorts of anomalous patches going on.

It appears something has gone wrong here. The Green dataset in particular looks like you shot clouds, or perhaps something in your optical train dewed over;

(this was th green channel binned to 35%, Crop, default AutoDev for diagnostics)

As such, I can understand you're having trouble getting anything useful in the visual spectrum,

That said, your Ha signal is fantastic and you can always create a false color Ha image if you want.

Once you do acquire a useful RGB signal, you will want to use the Compose module to process chrominance and luminance separately yet simultaneously. You can, for example, use Ha as luminance and R+Ha as red, with G and B as normal.

Hope this helps!

 

 

[Wyvernp]

I agree, I couldn't find much detail in the RGB data, Here's my quick attempt on it

I merged the rgb data and used that as Blue and green channels then added the Ha as red.

Edited March 31, 2020 by Wyvernp

[Notty]

11 hours ago, jager945 said:

Hi,

I had a quick look at the datasets. While the Ha signal is really nice, it seems the R, G and B data has all sorts of anomalous patches going on.

It appears something has gone wrong here. The Green dataset in particular looks like you shot clouds, or perhaps something in your optical train dewed over;

(this was th green channel binned to 35%, Crop, default AutoDev for diagnostics)

As such, I can understand you're having trouble getting anything useful in the visual spectrum,

That said, your Ha signal is fantastic and you can always create a false color Ha image if you want.

Once you do acquire a useful RGB signal, you will want to use the Compose module to process chrominance and luminance separately yet simultaneously. You can, for example, use Ha as luminance and R+Ha as red, with G and B as normal.

Hope this helps!

 

 

Hello, Ivo thanks so much for having a look at this. Re my poor RGB data, there was definitely no dew or clouds about.  I'm not experienced enough to look at that stretched G output and say whether that looks wrong or not! I've had a look at some of the individual subs and the flats definitely seem to have worked so I don't think that's the problem, and I used the same master dark for each channel, so I assume if there was a problem there is would manifest in the Ha image, but that seems to be calibrated nicely.  I'm wondering if light leakage could be a culprit? I assume Ha would be unaffected by it (relatively).

Anyone got any strategies for trouble shooting a leaking refractor? Unfortunately it's a Skywatcher so I believe it's all glued up and un-disassemblable.  I have upgraded the focuser and added a stepper motor so maybe that's a potential source.

Anyway I love your rendition above Ivo, can't believe how much detail you've teased out of it I'll have a go myself today. Andy

[Notty]

3 hours ago, Wyvernp said:

I agree, I couldn't find much detail in the RGB data, Here's my quick attempt on it

I merged the rgb data and used that as Blue and green channels then added the Ha as red.

That looks great! Thank you. So just to confirm, you combined RGB into one, and used that for both B&G?

[Wyvernp]

15 minutes ago, Notty said:

That looks great! Thank you. So just to confirm, you combined RGB into one, and used that for both B&G?

Yep exactly that. I used Photoshop rather than pix insight but should be similar result. Other tweaks were just levels, curves etc

Edited March 31, 2020 by Wyvernp

[Notty]

15 hours ago, Adreneline said:

Well this is a quick go - registered and background extracted and RGB channel combined and stretched in PI.

The Ha was layered with R in PS and then all the rest of the colour enhancement and noise reduction in PS.

I might try the binned images tomorrow but this is more the sort of colour I would expect for the Heart using Ha-RGB.

Hopefully someone else will have a go who has more skill than me in RGB processing.

Adrian

 

Thanks Adrian! Yes that's superior to what I was getting when I combined Ha with R, but I couldn't live with the loss of the Ha data, though you've done a better job preserving the detail than I did.